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* [PATCH v2 net] splice: do not checksum AF_UNIX sockets
@ 2024-12-10  5:06 Frederik Deweerdt
  2024-12-10  8:17 ` Kuniyuki Iwashima
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Frederik Deweerdt @ 2024-12-10  5:06 UTC (permalink / raw)
  To: netdev
  Cc: Frederik Deweerdt, David S. Miller, Eric Dumazet, Jakub Kicinski,
	Paolo Abeni, Simon Horman, Kuniyuki Iwashima, Michal Luczaj,
	David Howells, linux-kernel, xiyou.wangcong, David.Laight,
	jdamato, stable

When `skb_splice_from_iter` was introduced, it inadvertently added
checksumming for AF_UNIX sockets. This resulted in significant
slowdowns, for example when using sendfile over unix sockets.

Using the test code in [1] in my test setup (2G single core qemu),
the client receives a 1000M file in:
- without the patch: 1482ms (+/- 36ms)
- with the patch: 652.5ms (+/- 22.9ms)

This commit addresses the issue by marking checksumming as unnecessary in
`unix_stream_sendmsg`

Cc: stable@vger.kernel.org
Signed-off-by: Frederik Deweerdt <deweerdt.lkml@gmail.com>
Fixes: 2e910b95329c ("net: Add a function to splice pages into an skbuff for MSG_SPLICE_PAGES")
---
 net/unix/af_unix.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 001ccc55ef0f..6b1762300443 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2313,6 +2313,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 		fds_sent = true;
 
 		if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
 			err = skb_splice_from_iter(skb, &msg->msg_iter, size,
 						   sk->sk_allocation);
 			if (err < 0) {
-- 
2.44.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2024-12-12  4:30 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-12-10  5:06 [PATCH v2 net] splice: do not checksum AF_UNIX sockets Frederik Deweerdt
2024-12-10  8:17 ` Kuniyuki Iwashima
2024-12-10 16:10   ` Frederik Deweerdt
2024-12-10 16:12 ` Eric Dumazet
2024-12-10 16:28 ` Joe Damato
2024-12-12  4:30 ` patchwork-bot+netdevbpf

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